1. Technical Field
The present invention relates to a printing medium having a rectangular lens sheet formed in a predetermined lens shape on a surface thereof.
2. Related Art
In the related art, three-dimensional images are formed by the following methods: a method of using a lens sheet (hereinafter, referred to as a ‘lenticular sheet’) that has a lenticular lens including a plurality of cylindrical convex lenses arranged on a surface thereof; and a method of using a fly-eye lens having a plurality of convex lenses arranged in plan view, which is called integral photography.
In these methods, images for right and left eyes, that is, parallax images are arranged at positions corresponding to a plurality of lenses, so that a three-dimensional image is obtained due to the arranged parallax images. Therefore, when the parallax images are not arranged at exact positions corresponding to the lenses, it is difficult to obtain a three-dimensional image.
Therefore, a technique for directly printing parallax images on the lenticular sheet has been proposed in order to exactly align the parallax images with the lenses (for example, see Japanese Patent No. 3471930). In addition, a technique for leaving a portion of the lenticular sheet on the printing surface and for printing parallax images at positions corresponding to the lenses of the left portion of the lenticular sheet has been proposed (for example, see JP-A-2005-196153).
In addition to the printing techniques disclosed in Japanese Patent No. 3471930 and JP-A-2005-196153, in recent years, a user can easily print parallax images on a printing medium to form a three-dimensional image, due to a reduction in the manufacturing costs of the lenticular sheet and the proliferation of printers. In addition to printing parallax images on a printing medium to form a three-dimensional image, the user can send a printing medium having parallax images printed thereon to another person as a postcard.
Considering this situation, in the technique disclosed in Japanese Patent No. 3471930, in order to send the written lenticular sheet as a postcard, the user needs to write the addressee's name and address on the lenticular sheet having the parallax images printed thereon. In this case, when the user writes the addressee's name and address on the lenticular sheet, the addressee's name and address overlap the parallax images. In order to solve this problem, for example, the user needs to perform an operation of bonding a sheet that does not affect the parallax images even when the addressee's name and address are written over the parallax images by using an adhesive, while aligning the sheet with the lenticular sheet. When performing the bonding operation, the user must consider that the printing surface having the parallax images printed thereon is not contaminated and the printed parallax images are not peeled off. As a result, a large amount of work is required of the user.
In the technique disclosed in JP-A-2005-196153, a parallax image cannot be printed on a portion of the lenticular lens remaining on the printing surface having the parallax image printed thereon. Therefore, for example, when a lenticular sheet is sent as a postcard, it is difficult to use the entire surface of the postcard as a surface for forming a three-dimensional image.